This invention relates, in general, to the treatment of a production interval of a wellbore to stimulate hydrocarbon production and prevent the production of fine particulate materials and, in particular, to a screen assembly having diverter members and a method for progressively gravel packing or progressively frac packing the production interval of the wellbore.
It is well known in the subterranean well drilling and completion art that relatively fine particulate materials may be produced during the production of hydrocarbons from a well that traverses an unconsolidated or loosely consolidated formation. Numerous problems may occur as a result of the production of such particulate. For example, the particulate causes abrasive wear to components within the well, such as tubing, pumps and valves. In addition, the particulate may partially or fully clog the well creating the need for an expensive workover. Also, if the particulate matter is produced to the surface, it must be removed from the hydrocarbon fluids using surface processing equipment.
One method for preventing the production of such particulate material is to gravel pack the well adjacent to the unconsolidated or loosely consolidated production interval. In a typical gravel pack completion, a sand control screen is lowered into the wellbore on a work string to a position proximate the desired production interval. A fluid slurry including a liquid carrier and a relatively coarse particulate material, such as sand, gravel or proppants which are typically sized and graded and which are typically referred to herein as gravel, is then pumped down the work string and into the well annulus formed between the sand control screen and the perforated well casing or open hole production zone.
The liquid carrier either flows into the formation or returns to the surface by flowing through a wash pipe or both. In either case, the gravel is deposited around the sand control screen to form the gravel pack, which is highly permeable to the flow of hydrocarbon fluids but blocks the flow of the fine particulate materials carried in the hydrocarbon fluids. As such, gravel packs can successfully prevent the problems associated with the production of these particulate materials from the formation.
It is sometimes desirable to perform a formation fracturing and propping operation prior to or simultaneously with the gravel packing operation. Hydraulic fracturing of a hydrocarbon formation is sometimes necessary to increase the permeability of the production interval adjacent the wellbore. According to conventional practice, a fracture fluid such as water, oil, oil/water emulsion, gelled water, gelled oil, CO2 and nitrogen foams or water/alcohol mixture is pumped down the work string with sufficient volume and pressure to open multiple fractures in the production interval. The fracture fluid may carry a suitable propping agent, such as sand, gravel or proppants, which are typically referred to herein as proppants, into the fractures for the purpose of holding the fractures open following the fracturing operation.
The fracture fluid must be forced into the formation at a flow rate great enough to generated the required pressure to fracture the formation allowing the entrained proppant to enter the fractures and prop the formation structures apart, producing channels which will create highly conductive paths reaching out into the production interval, and thereby increasing the reservoir permeability in the fracture region. As such, the success of the fracture operation is dependent upon the ability to inject large volumes of hydraulic fracture fluid along the entire length of the formation at a high pressure and at a high flow rate.
It has been found, however, that it is difficult to achieve a complete gravel pack of the desired production interval either independent of or as part of a fracturing operation, particularly in long or inclined/horizontal production intervals. These incomplete packs are commonly a result of the liquid carrier entering the more permeable portions of the production interval causing the gravel to form a sand bridge in the annulus. Thereafter, the sand bridge prevents the gravel pack slurry from flowing to the remainder of the annulus which, in turn, prevents the placement of sufficient gravel in the remainder of the annulus.
Therefore a need has arisen for a screen assembly and a method that are capable of creating fractures along the entire length of a production interval. A need has also arisen for such a screen assembly and a method that can produce a complete gravel pack of the wellbore adjacent to the production interval either independent of or as part of the fracturing of the production interval. Further, a need has arisen for a screen assembly and a method that are capable of stimulating the production interval to enhance production and gravel packing the production interval to prevent the production of fine particulate materials when production commences.
The present invention disclosed herein comprises a screen assembly and a method that are capable of enhancing production from a production interval by creating fractures throughout the entire interval and producing a substantially complete gravel pack of the wellbore adjacent to the production interval to prevent the production of fine particulate materials when production commences. The screen assembly and the method of the present invention achieve these results by progressively treating the production interval from one end to the other.
The screen assembly comprises a sand control screen that is positioned within the wellbore and a plurality of diverter members positioned along the sand control screen. The diverter members progressively allow fluid communication from the interior of the screen assembly to the exterior of the screen assembly from a first end to a second end of the interval, thereby delivering the treatment fluid along the entire length of the interval.
The diverter members may comprise a plurality of actuatable members. The actuatable devices may be rupture disks, pressure actuated one-way valves or other pressure actuated devices that are positioned along the sand control screen such that the pressure required to actuate the actuatable members progressively increases from the first end to the second end of the interval. Alternatively, the actuatable members may be progressively actuated from the first end to the second end of the interval using signals sent from the surface using hard wire connections, fiber optics, hydraulics or wireless telemetry.
The sand control screen may include a base pipe having a plurality of perforation therethrough. A filter medium is positioned around the base pipe. A seal member initially prevents the flow of fluid through the perforations. The seal member may comprise propellant members that are combustibly removable. The seal member may alternatively comprise friable members that are sonically removable. As yet another alternative, the seal member may consist of a plurality of plugs, one plug for each perforation. The plugs may be chemically of mechanically removable.
The method of the present invention comprises traversing the formation with the wellbore, locating a screen assembly including a sand control screen and a plurality of diverter members within the wellbore proximate the formation, injecting a treatment fluid into the interior of the screen assembly, progressive operation the diverter members to establish fluid communication between the interior of the screen assembly and the exterior of the screen assembly from the first end to the second end of the interval and terminating the injecting when the complete interval is treated.